Airsacculitis - Molds Isolated from Lungs of Broilers from Slaughterhouse under Control of the Federal Inspection Service

Abstract

Background: Molds are filamentous saprophytic fungi with worldwide distribution, which are found in various environmental substrates. Among them, the Aspergillus genus stands out as one of the main causes of lung disease. Commercial poultry such as chickens and turkeys, as well as captive and free-ranging wild birds species are most frequently affected. The infection occurs by the inhalation of conidia, which are dispersed in the air by wind. The most frequent acute clinical manifestation is usually observed in young animals, often with episodes of outbreaks in poultry farms, whereas chronic disease is more frequently observed in adult birds. In slaughterhouses, carcass inspection is very important for the detection of certain diseases and for monitoring their occurrence. The objective of this study was to assess the occurrence of aerosacculitis caused by molds in commercial broilers slaughtered in one establishment under Federal Inspection Service (SIF) through mycological, histopathological and molecular diagnosis.
Materials, Methods & Results: The samples (n = 76) came from 9 flocks localized in the Vale do Taquari - State of Rio Grande do Sul, RS, Brazil. Lungs were collected from broilers with airsacculitis, directly from the slaughter line and kept under refrigeration (4 oC). The evaluation and condemnation of carcasses were performed by the sanitary inspection department of the slaughterhouse. The molds were identified as the causal agent through fungal culture, histopathology and PCR analysis. Sixteen (21.0%) lung samples were positive in mycological culture, being Aspergillus sections Fumigati and Flavi the most frequent, and 2 (2.7%) samples showed fungal elements (hyaline, branching septate hyphae). The respective isolates were identified as Aspergillus fumigatus sensu stricto following the amplification of β-tub gene fragments and gel electrophoresis. Among the remaining 58 samples: no fungal growth in 61.9% (47/76) cultures and in 14.4% (11/76) were isolated colonies of hyaline septate fungi and of zygomycetes which were considered as common environmental fungi belonged to genera: Aspergillus, Penicillium, Fusarium, Scopulariopsis, Mucor and Rhizopus.
Discussion: Poultry become infected through aspiration in large numbers of conidia of molds. According to the literature,
A. fumigatus sensu stricto, which belongs to the section Fumigati, is the most ubiquitous in the environment and frequently associated with lung diseases in humans and animals. Identification of fungi to species level is important in order to determine the etiology of the disease and also to detect potential novel agents. Our results corroborate previous studies that showed A. fumigatus to be the prevalent etiological agent identified in commercial poultry. Although in smaller quantities, isolates of the section Flavi were also recovered from the lungs of healthy chickens. In the present study, only A. fumigatus was cultivated from airsacculitis cases. In poultry, many environmental factors may be present and influence the development of aspergillosis, including excessive ammonia and humidity, inadequate temperature and degraded litter. Our results are in agreement with other research where Aspergillus was detected in the lungs of chicken condemned by the inspection service. The eco-epidemiology of Aspergillus sections Fumigati and Flavi needs to be reevaluated, especially considering the transmission from environment to animals and humans. Further studies should be conducted in order to correlate clinical aspects with molecular diversity and antifungal profile among Aspergillus, as well as, investigate mold diversity isolated from commercial poultry in locations where the poultry industry is economically significant.

Keywords: moulds, Aspergillus spp., Aspergillus section Fumigati, Aspergillus section Flavi, poultry, airsacculitis.